<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        div{
            width:100px;
            height:100px;
            background-color: red;
            color:white;
            margin:10px;
        }
        div:nth-child(2){
            /* display:none;none,元素隐藏，并且将元素空间一并隐藏;block 显示 */
            visibility:hidden;/*hidden,元素隐藏，修改元素透明度，不隐藏空间*/
        }
        td{
            width:20px;
            height:10px;
            border:1px solid black;
        }
        table{
            border-collapse:collapse;
            caption-side:bottom;
        }
    </style>
</head>
<body>
   <table><!--cellspacing="0",单元格间距为0-->
       <caption>学生信息表</caption>
       <colgroup><!--用来控制列的标签，写在所有tr之上-->
            <col style="background-color: blanchedalmond;">
            <col style="background-color: red;">
            <col style="background-color: yellow;" span="2"><!--span属性第三列控制两列-->
            <!-- <col style="background-color:pink;"> -->
       </colgroup>
           <tr>
               <td></td>
               <td></td>
               <td></td>
               <td></td>
           </tr>
           <tr>
            <td></td>
            <td></td>
            <td></td>
            <td></td>
        </tr>
        <tr>
            <td></td>
            <td></td>
            <td></td>
            <td></td>
        </tr>
        <tr>
            <td></td>
            <td></td>
            <td></td>
            <td></td>
        </tr>
   </table> 
       <div>div1</div>
       <div>div2</div>
       <div>div3</div>
</body>
</html>